NOT_EXISTS_CONV : conv
STRUCTURE
Conv
SYNOPSIS
Moves negation inwards through an existential quantification.
DESCRIPTION
When applied to a term of the form ~(?x.P), the conversion NOT_EXISTS_CONV returns the theorem: 
   |- ~(?x.P) = !x.~P

FAILURE
Fails if applied to a term not of the form ~(?x.P).
SEEALSO
EXISTS_NOT_CONV, FORALL_NOT_CONV, NOT_FORALL_CONV
HOL  Kananaskis-14